Flowing Bubbles Mimic Computer

The team, based at MIT's Center for Bits and Atoms, reports that the bubbles in their microfluidic device can carry on-chip process control information, just like the electronic circuits of a traditional microprocessor, while also performing chemical reactions.

"Bubble logic merges chemistry with computation, allowing a digital bit to carry a chemical payload. Until now, there was a clear distinction between the materials in a reaction and the mechanisms to control them," said co-author Neil Gershenfeld, director of the Center for Bits and Atoms and associate professor of media arts and sciences.

Microfluidics has the potential to revolutionize large-scale chemical analysis and synthesis, environmental and medical testing and industrial production processes, but applications outside of the laboratory have been limited so far by the external control systems-valves and plumbing-required for its operation.

But now, the MIT researchers are able to control microfluidic chips via the interactions of bubbles flowing through microchannels, eliminating the need for external controls. The researchers modelled their new microfluidic chips on the architecture of existing digital circuits. But instead of using high and low voltages to represent a bit of information, they use the presence or absence of a bubble. They report on nitrogen bubbles in water, but any other combinations of materials that don't mix would work, such as oil and water.

Controlling chemical reactions will likely be a primary application for the chips, according to the researchers. It will be possible to create large-scale microfluidic systems such as chemical memories, which store thousands of reagents on a chip, using counters to dispense exact amounts and logic circuits to deliver them to specific destinations.